Hypertension imparts a series of complex humoral and mechanical signals to the arterial wall that result in the development of an inflammatory state. Recent studies have implicated the production of reactive oxygen species as central to the pathogenesis of hypertensive vascular pathology. In this application, we propose to test the hypothesis that in the setting of hypertension, local production of hydrogen peroxide by vascular smooth muscle cells, endothelial cells and/or resident macrophages is a pivotal signaling event in the inflammatory responses that occur in the hypertensive arterial wall. To accomplish this overall objective we have developed a novel transgenic mouse that will allow tissue-specific overexpression of catalase. Through these studies we will be able to modify local H2O2 production at the cellular level and determine the subsequent effects on production of reactive oxygen species, inflammatory gene expression and the development of hypertension-induced atherosclerosis. The proposed specific aims are: I: To determine the effects of smooth muscle-specific overexpression of catalase on the development of hypertension-induced inflammation and atherosclerosis. II: Examine the comparative effects of macrophage-specific overexpression of catalase on the vascular consequences of hypertension. III: To determine the potential functional contributions endothelial-specific overexpression of catalase on vascular function, inflammation and the progression of hypertension-induced atherosclerosis. PUBLIC HEALTH RELEVANCE: Hypertension is a major health problem in the United States today. The pathological consequences of hypertension are myriad and include atherosclerosis, stroke, heart failure, kidney failure and other end organ disease. The proposed studies in this application will investigate the potential role of localized H2O2 production in vascular inflammatory responses in an effort to define the causal role of H2O2 in the pathogenesis of hypertensive vascular disease.